1. Field of the Invention
The present invention relates to a tray for delivering medication to the teeth and/or gingiva of a dental patient. More particularly, the field of the present invention concerns a dental medication delivery tray that is custom-made to closely match the configuration of at least part of a patient's dental arch.
2. Description of the Related Art
A variety of methods have been proposed in the past to deliver medication to the teeth and/or gingiva (i.e., the gum tissue) of a dental patient. One method of applying medication to teeth involves direct application of the medication to the tooth surface by the use of a brush, swab or the like. This method is relatively inexpensive and can be carried out either by the dental practitioner or by the patient.
Unfortunately, the direct application of a medicant to oral structures is generally unsatisfactory because the medication typically does not remain on the oral structure for a significant length of time. The length of time is variable and may depend on factors such as the viscosity of the medication, the presence of saliva and the ability of the patient to prevent adjacent soft tissues such as inner surfaces of the labia or lips and bucca or cheeks from contacting the tray containing the medication. In many instances, the effectiveness of the medication is substantially diminished if the medication is prematurely removed from the oral structure under treatment.
Another common method for delivering medication to teeth involves the use of a dental tray that is placed over the dental arch. The tray has a channel that receives the teeth and has a length that is sufficient to receive all or at least a portion of the dental arch. In some instances, the channel has a sufficient depth to receive a portion of the gingiva along with the teeth.
Many dental medication delivery trays are mass-produced and not custom made to closely fit the dental arch of a particular patient. Although such trays are relatively inexpensive, they are often considered quite bulky and unpleasant to wear for any significant length of time. Additionally, some mass-produced dental trays do not retain medication against the oral structures under treatment unless the patient remains relatively immobile.
Dental trays that are custom-made to closely fit the dental arch of a patient are considered by many to represent a significant improvement over mass-produced dental trays. The close fit provided by custom-made trays largely avoids unnecessary void spaces that are common with mass-produced dental trays. Most custom-made trays are less obtrusive in the mouth than mass-produced trays, and as such are more comfortable to wear for extended periods of time.
One technique of making a custom dental tray involves taking an alginate impression of a patient's dental structure, and then making a model or casting from the impression. Next, a thin sheet of heat softenable plastic material is placed over the casting and heated, causing the plastic sheet to drape over the model and ultimately form a configuration that closely matches the shape of the underlying model. The tray is then trimmed as needed.
One of the most common uses of both mass-produced and custom-made dental medication trays is in connection with a bleaching gel or solution to whiten the patient's teeth. Many individuals desire whiter teeth and seek to eliminate or at least reduce the discoloration of stained teeth. Tooth stains are caused by a variety of sources, including food and beverages, drugs (such as tetracycline), tobacco products and poor oral hygiene.
When dental trays are used for bleaching teeth at home, the patient is typically instructed to place an amount of bleaching solution into a corresponding area of the tray for each tooth to be treated. The tray is then placed over the dental arch. Often, the bleaching solution is changed every 0.5 to 2.5 hours and the tray is removed during meals. Sometimes a recommendation is made to wear the dental tray overnight. The efficacy of the bleaching procedure depends on factors such as the type and intensity of the stain, the bleaching agent contact time on the tooth surfaces, the amount of available active ingredient in the bleaching solution as well as patient acceptance and adherence to the procedure.
Unfortunately, the volume of bleaching solution that is available in conventional trays tends to diminish rapidly over time, thereby decreasing the amount of active ingredient available for bleaching the teeth. Test results in the April, 1997 issue of the Clinical Research Associates Newsletter show that in many instances after 30 minutes, less than 50% of the original quantity of bleaching agent was available for bleaching activity. The same test results show that in many instances after one hour, less than 25% of the bleaching agent was available for bleaching activity. Consequently, it is often recommended to replenish the bleaching agents in conventional trays about every 15 to 30 minutes in order to maintain the most efficacious dosage of bleaching agent in contact with the tooth.
Unfortunately, the daytime schedules of many patients do not easily accommodate periodic, continuous replenishment of the bleaching agent. In addition, periodically replenishing the bleaching agent during the night is unrealistic for many patients. Since patient adherence to the procedure determines the ultimate success of the treatment program, the need to constantly replenish the dental bleaching solution is a major obstruction that limits the success of the treatment.